Question

A 100 m wire having resistance 20 ohm and radius 0.3mm , find resistivity of this material.

Answer 1

Explanation:

R=ρl/A

A=pie.r^2

r=0.3×10^-3m=3×10^-4

A=3.18×9×10^-8

l=100m

R=20ohm

ρ=R.A/L

=20×28.3×10^-8/100

572×10^-10 ohm m^-1

Answer 2

Explanation:

R=rho multiplied by length divided by area of cross section

20 = rho 100 ×1000 ×1000/ π0.3×0.3